cc/layers/viewport.cc

   1 // Copyright 2015 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "cc/layers/viewport.h"
   6
   7 #include "base/logging.h"
   8 #include "cc/input/top_controls_manager.h"
   9 #include "cc/trees/layer_tree_host_impl.h"
  10 #include "cc/trees/layer_tree_impl.h"
  11 #include "ui/gfx/geometry/vector2d_conversions.h"
  12 #include "ui/gfx/geometry/vector2d_f.h"
  13
  14 namespace cc {
  15
  16 // static
  17 scoped_ptr<Viewport> Viewport::Create(
  18     LayerTreeHostImpl* host_impl) {
  19   return make_scoped_ptr(new Viewport(host_impl));
  20 }
  21
  22 Viewport::Viewport(LayerTreeHostImpl* host_impl)
  23     : host_impl_(host_impl)
  24     , pinch_zoom_active_(false) {
  25   DCHECK(host_impl_);
  26 }
  27
  28 void Viewport::Pan(const gfx::Vector2dF& delta) {
  29   gfx::Vector2dF pending_delta = delta;
  30   float page_scale = host_impl_->active_tree()->current_page_scale_factor();
  31   pending_delta.Scale(1 / page_scale);
  32   InnerScrollLayer()->ScrollBy(pending_delta);
  33 }
  34
  35 Viewport::ScrollResult Viewport::ScrollBy(const gfx::Vector2dF& delta,
  36                                           const gfx::Point& viewport_point,
  37                                           bool is_direct_manipulation,
  38                                           bool affect_top_controls) {
  39   gfx::Vector2dF content_delta = delta;
  40
  41   if (affect_top_controls && ShouldTopControlsConsumeScroll(delta))
  42     content_delta -= ScrollTopControls(delta);
  43
  44   gfx::Vector2dF pending_content_delta = content_delta;
  45
  46   pending_content_delta -= host_impl_->ScrollLayer(InnerScrollLayer(),
  47                                                    pending_content_delta,
  48                                                    viewport_point,
  49                                                    is_direct_manipulation);
  50
  51   ScrollResult result;
  52
  53   // TODO(bokan): This shouldn't be needed but removing it causes subtle
  54   // viewport movement during top controls manipulation.
  55   if (gfx::ToRoundedVector2d(pending_content_delta).IsZero()) {
  56     result.consumed_delta = delta;
  57   } else {
  58     pending_content_delta -= host_impl_->ScrollLayer(OuterScrollLayer(),
  59                                                      pending_content_delta,
  60                                                      viewport_point,
  61                                                      is_direct_manipulation);
  62     result.consumed_delta = delta - AdjustOverscroll(pending_content_delta);
  63   }
  64
  65   result.content_scrolled_delta = content_delta - pending_content_delta;
  66   return result;
  67 }
  68
  69 void Viewport::SnapPinchAnchorIfWithinMargin(const gfx::Point& anchor) {
  70   gfx::SizeF viewport_size =
  71       host_impl_->active_tree()->InnerViewportContainerLayer()->bounds();
  72
  73   if (anchor.x() < kPinchZoomSnapMarginDips)
  74     pinch_anchor_adjustment_.set_x(-anchor.x());
  75   else if (anchor.x() > viewport_size.width() - kPinchZoomSnapMarginDips)
  76     pinch_anchor_adjustment_.set_x(viewport_size.width() - anchor.x());
  77
  78   if (anchor.y() < kPinchZoomSnapMarginDips)
  79     pinch_anchor_adjustment_.set_y(-anchor.y());
  80   else if (anchor.y() > viewport_size.height() - kPinchZoomSnapMarginDips)
  81     pinch_anchor_adjustment_.set_y(viewport_size.height() - anchor.y());
  82 }
  83
  84 void Viewport::PinchUpdate(float magnify_delta, const gfx::Point& anchor) {
  85   if (!pinch_zoom_active_) {
  86     // If this is the first pinch update and the pinch is within a margin-
  87     // length of the screen edge, offset all updates by the amount so that we
  88     // effectively snap the pinch zoom to the edge of the screen. This makes it
  89     // easy to zoom in on position: fixed elements.
  90     SnapPinchAnchorIfWithinMargin(anchor);
  91
  92     pinch_zoom_active_ = true;
  93   }
  94
  95   LayerTreeImpl* active_tree = host_impl_->active_tree();
  96
  97   // Keep the center-of-pinch anchor specified by (x, y) in a stable
  98   // position over the course of the magnify.
  99   gfx::Point adjusted_anchor = anchor + pinch_anchor_adjustment_;
 100   float page_scale = active_tree->current_page_scale_factor();
 101   gfx::PointF previous_scale_anchor =
 102       gfx::ScalePoint(adjusted_anchor, 1.f / page_scale);
 103   active_tree->SetPageScaleOnActiveTree(page_scale * magnify_delta);
 104   page_scale = active_tree->current_page_scale_factor();
 105   gfx::PointF new_scale_anchor =
 106       gfx::ScalePoint(adjusted_anchor, 1.f / page_scale);
 107   gfx::Vector2dF move = previous_scale_anchor - new_scale_anchor;
 108
 109   // Scale back to viewport space since that's the coordinate space ScrollBy
 110   // uses.
 111   move.Scale(page_scale);
 112
 113   // If clamping the inner viewport scroll offset causes a change, it should
 114   // be accounted for from the intended move.
 115   move -= InnerScrollLayer()->ClampScrollToMaxScrollOffset();
 116
 117   Pan(move);
 118 }
 119
 120 void Viewport::PinchEnd() {
 121   pinch_anchor_adjustment_ = gfx::Vector2d();
 122   pinch_zoom_active_ = false;
 123 }
 124
 125 gfx::Vector2dF Viewport::ScrollTopControls(const gfx::Vector2dF& delta) {
 126   gfx::Vector2dF excess_delta =
 127       host_impl_->top_controls_manager()->ScrollBy(delta);
 128
 129   return delta - excess_delta;
 130 }
 131
 132 bool Viewport::ShouldTopControlsConsumeScroll(
 133     const gfx::Vector2dF& scroll_delta) const {
 134   // Always consume if it's in the direction to show the top controls.
 135   if (scroll_delta.y() < 0)
 136     return true;
 137
 138   if (TotalScrollOffset().y() < MaxTotalScrollOffset().y())
 139     return true;
 140
 141   return false;
 142 }
 143
 144 gfx::Vector2dF Viewport::AdjustOverscroll(const gfx::Vector2dF& delta) const {
 145   // TODO(tdresser): Use a more rational epsilon. See crbug.com/510550 for
 146   // details.
 147   const float kEpsilon = 0.1f;
 148   gfx::Vector2dF adjusted = delta;
 149
 150   if (std::abs(adjusted.x()) < kEpsilon)
 151     adjusted.set_x(0.0f);
 152   if (std::abs(adjusted.y()) < kEpsilon)
 153     adjusted.set_y(0.0f);
 154
 155   return adjusted;
 156 }
 157
 158 gfx::ScrollOffset Viewport::MaxTotalScrollOffset() const {
 159   gfx::ScrollOffset offset;
 160
 161   offset += InnerScrollLayer()->MaxScrollOffset();
 162
 163   if (OuterScrollLayer())
 164     offset += OuterScrollLayer()->MaxScrollOffset();
 165
 166   return offset;
 167 }
 168
 169 gfx::ScrollOffset Viewport::TotalScrollOffset() const {
 170   gfx::ScrollOffset offset;
 171
 172   offset += InnerScrollLayer()->CurrentScrollOffset();
 173
 174   if (OuterScrollLayer())
 175     offset += OuterScrollLayer()->CurrentScrollOffset();
 176
 177   return offset;
 178 }
 179
 180 LayerImpl* Viewport::InnerScrollLayer() const {
 181   return host_impl_->InnerViewportScrollLayer();
 182 }
 183
 184 LayerImpl* Viewport::OuterScrollLayer() const {
 185   return host_impl_->OuterViewportScrollLayer();
 186 }
 187
 188 }  // namespace cc